The present invention relates generally to clutches, and in particular to clutches for motor vehicles; more specifically, the invention concerns that part of these clutches which is commonly referred to as the clutch mechanism or cover assembly, which, forming a unitary assembly, is connected to the reaction plate after the insertion of a friction disc.
In general terms, a clutch mechanism of this kind comprises a first substantially annular part generally referred to as the cover, a second substantially annular part generally referred to as the pressure plate, which is connected for rotation with the cover by coupling means which allow the pressure plate to be axially displaced relative to the cover, and between the cover and the pressure plate, axially acting elastic means which bear on the cover and which urge the pressure plate in a direction away from the said cover.
For example, in a mechanism for a diaphragm clutch, the axially acting elastic means consist of the periphery of a third annular part comprising a diaphragm spring, the central part of which is divided up into radial fingers for controlling the release of the periphery, and means for mounting the diaphragm for rocking movement on the cover, the said diaphragm bearing on the pressure plate by its said peripheral part.
The present invention concerns the case where the clutch mechanism in question is intended to be connected to a flat reaction plate, that is to say a reaction plate devoid of any axially-extending lateral wall at its periphery, or a slightly hollow reaction plate, that is to say a reaction plate provided, at this periphery, with a lateral wall of reduced axial extension, which at most extends over the friction disc.
In such a case, it is the cover which possesses a lateral wall extending parallel to its axis, in order to define this space. In certain embodiments, this lateral wall is integral with the transverse wall, or base, on which the axially acting elastic means bear.
In other embodiments, the lateral wall of the cover is divided up into wall elements, forming a raised part, these elements being joined to the transverse wall of the cover, parallel to its axis, as described, for example, in French Pat. No. 2,300,933, and also in the addition to this U.S. Pat. No. 2,339,099.
In general terms, in clutch mechanisms, it is desirable to limit the axial distance through which a pressure plate is capable of travelling due to the pressure of the axially acting elastic means.
This applies in particular, during the storage of a clutch mechanism of this kind, before it is mounted on a reaction plate, because if the pressure plate, which at this stage is not axially buttressed by the reaction plate, does not have a limited axial movement, damage can result to the coupling means connecting it to the cover, particularly in the case of simple strips which only offer a moderate axial resistance.
It is for this reason that provision is usually made to associate, with the pressure plate, abutment means which are suitable for axially retaining the pressure plate after a predetermined axial distance of travel relative to the cover.
Most frequently, these abutment means comprise a transverse bearing shoulder which is integral with the pressure plate and which is located on the other side of the cover relative to this pressure plate, for cooperation with this cover, this bearing shoulder in practice being formed at the end of an axially projecting pin with which the pressure plate is equipped for this purpose.
However, a reverse arrangement has already been proposed, in particular in French Pat. No. 1,580,169, which relates to a mechanism intended to be joined to a reaction plate of the hollow kind, in which the transverse bearing shoulder employed is formed on a particular part which is separate from the cover and which is joined to the latter when the mechanism is assembled; this inevitably complicates the assembly step.
The present invention relates in general terms to a clutch mechanism which is more particularly, but not essentially intended to be fitted to a flat reaction plate and which is equipped with a bearing shoulder for the pressure plate integral with the cover.